This invention relates to toilet apparatus, and in particular to such apparatus that uses little water in each flushing cycle.
A conventional toilet or water closet disposes of waste matter by hydraulic means alone by relying on a large enough volume of water to generate sufficient force to expel waste from the toilet pan. Many toilet systems exist which dispose of waste matter with a negative pneumatic pressure e.g. by drawing waste from the pan through an outlet pipe using various valves, pumps, vacuum chambers, transfer tanks and the like. Such systems do reduce water consumption but are generally difficult to manufacture, and are inconvenient to install, use and maintain.
U.S. Pat. No. 4,306,321 discloses a water closet for boats and caravans in which a sealed chamber, which includes the toilet pan, is pressurized to discharge the contents of the pan through a discharge valve into a holding tank, the chamber being subsequently pressurised again to discharge flushing water through the outlet valve to clean the valve. DE-A-19 623 331 and FR-A-2 696 200 both provide flushing water under pressure to a sealed pan/chamber to flush the contents of the pan through an outlet pipe, but make no provision for increasing the pressure in the chamber.
It is an object of the present invention to obviate or mitigate these difficulties by providing toilet apparatus which uses a positive pressure to discharge waste matter from the pan to an outlet pipe thus reducing water consumption. Such apparatus has the additional advantage that as the outlet pipe is unobstructed by valves or other equipment the toilet can also be used in a conventional way.
The present invention is toilet apparatus comprising a toilet pan, an outlet pipe for the contents of the pan a closeable lid on the pan forming with the pan a waste receptacle chamber, a seal between the lid and the pan, means for introducing water into the chamber to wash the internal surface of the pan, and means for subsequently increasing the air pressure in the chamber to force the contents of the pan through the outlet pipe.
Preferably, means are provided to pressurise the water introduced to wash the internal surface of the pan.
The lid may be provided with a locking mechanism for securing the lid in its closed position.
A locking sensor may be associated with the locking mechanism to detect locking of the lid and initiate operation of the apparatus.
In a preferred embodiment of the invention, the outlet pipe is formed with an S-bend water trap.
The means for increasing the air pressure in the chamber may include an air displacement unit connected to the chamber and, preferably also to the water cistern. The unit may comprise a piston movable in a cylinder. The piston moving in the cylinder in one stroke displaces a volume of air sufficient to provide the pressure in the chamber required to expel the contents of the pan. The piston may be double acting, the other stroke of the piston providing the air to pressurise the cistern and thus the water washing the internal surface of the pan before the contents of the pan are expelled.
The pan is provided with inlets for the water for washing its surface, these inlets being located at the top of the pan and being connected to the cistern by means which prevent the escape of air from the chamber.
Preferably, a cistern is connected to the pan by two pipes each incorporating siphon. One pipe is normally closed but may be opened manually to actuate the siphon, while the other pipe is open and may act as an overflow outlet. The cistern is provided with an aperture sufficient to relay pneumatic pressure and is connected to the air displacement unit. When the air displacement unit is activated, the displaced air pressurises the cistern and, all vents and pipes to the exterior being closed, the water in the cistern is forced through the open siphon and into the pan. By venting the overflow pipe when the water level falls to a predetermined level, the pressure in the cistern can be released while allowing continued siphonic flow from the cistern to the pan.
Operation of the air displacement unit may be triggered by the locking of the lid, the locking action being detected by a sensor.
The toilet apparatus may be fitted with a tipping/holding/siphon tank which may be pneumatically actuated/emptied.